Two-point Search

This article summarizes some of the binary search variants, most of which come from Leetcode

1. (leetcode) Search in rotated Sorted Array

(i.e., 0 1 2 4 5 6 7 might become 4 5 6 7 0 1 2).

 Public intSearchint[] Nums,intkey) {        intLo =0, hi = nums.length-1;  while(Lo <=hi) {            intMid = lo + (hi-lo)/2; if(Nums[mid] = = key)returnmid; if(Nums[mid] < Nums[hi]) {//right Half ordered                if(Nums[mid] < key && Key <=Nums[hi]) {Lo= Mid +1;//key falls in the ordered part}Else{//Otherwise the key falls in the unordered partHi = Mid-1; }            }Else{//left half ordered                if(Nums[lo] <= key && Key <Nums[mid]) {Hi= Mid-1;//key falls in the ordered part}Else{//Otherwise the key falls in the unordered partLo = mid +1; }            }        }        return-1; }

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2. (Leetcode Bayi) Search in rotated Sorted Array II

(i.e. 1 2 4 4 4 4 4 might become 4 4 4 1 2 4 4).

//about the last nums[mid] = = nums [Hi] Situation//1 2 1) 1 1//l m H-hi--; //1 2 1) 1 1//l m H     PublicBoolean Search (int[] Nums,inttarget) {        if(NULL= = Nums | | Nums.length <0)return false; intLo =0, hi = nums.length-1;  while(Lo <=hi) {            intMid = lo + (hi-lo)/2; //Get It            if(Nums[mid] = = target)return true; //find an ordered section to find            if(Nums[mid] < Nums[hi]) {//The second part is ordered                if(Nums[mid] < target && Target <=Nums[hi]) {Lo= Mid +1; }Else{Hi= Mid-1; }             }Else if(Nums[mid] > Nums[hi]) {//first half ordered                if(Nums[lo] <= target && Target <Nums[mid]) {Hi= Mid-1; } Else{lo= Mid +1; }            }Else{//Nums[mid] = = Nums[hi]Hi-- ; }        }        return false; }

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3. Find Minimum in rotated Sorted Array

In the rotated array, find the smallest number

If NUMS[MID] > Nums[hi] min falls in [Mid+1, HI]

If NUMS[MID] < Nums[hi] min falls on [0, Mid]

  Public intFindmin (int[] nums) {        intLo =0, hi = nums.length-1;  while(Lo <hi) {            intMid = lo + (hi-lo)/2 ; //mid > Hi,min in [Mid+1,hi]            if(Nums[mid] >Nums[hi]) {Lo= Mid +1; }            //Mid < Hi, min in [0,mid]            if(Nums[mid] <Nums[hi]) {Hi=mid; }        }        returnNums[lo]; }

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4. Find Minimum in rotated Sorted Array II

Same as the last topic, but with a repetition, the same as the idea of topic 1-2

If NUMS[MID] > Nums[hi] min falls in [Mid+1, HI]

If NUMS[MID] < Nums[hi] min falls on [0, Mid]

If nums[mid] = = Nums[hi] Then make further judgments after hi--

   Public intFindmin (int[] nums) {        intLo =0, hi = nums.length-1;  while(Lo <hi) {            intMid = lo + (hi-lo)/2; if(Nums[mid] >Nums[hi]) {Lo= Mid +1; }Else if(Nums[mid] <Nums[hi]) {Hi=mid; }Else{Hi--; }        }        returnNums[lo]; }

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Two-point Search